Manufacture of electromagnetic relay



March 2, 1965 J. 5. ZIMMER 3,171,190

MANUFACTURE OF ELECTROMAGNETIC RELAY Original Filed Jan. 21, 1959 2 Sheets-Sheet 1 2 5 2' t9 5 a E u o 5 3 (O FIGJ INVENTOR TERMINAL JOHN S. ZIMMER,

"March 2,;1965 J. 5. ZIMMER 0 MANUFACTURE OF ELECTROMAGNETIC RELAY Original Filed Jan. 21, 1959 2 Sheets-Sheet 2 TERMINAL NO-l F IGS swncume TERMINAL TERMINAL No.2

INVENTORZ JOHN s. ZIMMER,

UM M ATTORNEY.

United States Patent ,1 1, 99 MANUFACTURE OF ELEQTROMAGNETIC RELAY John S. Zimme'i', Wayneslioro, Va., assignor 'toGeneral Electric Company {a corporation of New York Original application Jan. 21, 1959, Ser. N0.788,197 now Patent No. 2,993,104, dated July 18, 1961. D vided and this application May 3, 1-961, Ser. No. 107,448

- Claims. '(Cll 29-1555) The invention relates to the manufacture of an electromagnetic relay, and particularlyto a method that permits an. electromagnetic relay of relatively small dimensions to be manufactured in large quantities. 'This is a divisional application of my tie-pending application entitled Electromagnetic Relay, which was filed January 21, 1259,, and assigned Serial No. 788,197, now Patent No. 2,993,104. An object of the invention is to provide an improved meth od of manufacturing an electromagnetic relay.

Another object of the invention is to provide an improved method of manufacture that permits a relatively small electromagnetic relay to be manufactured with mass-production methods.

These and other objects are accomplished in accordance with the invention by an electromagnetic relay which, briefly, comprises a core having first and second elements of magnetic material, the two elements being separated by a gap. An elongated spring has one end fastened to the first core element and the other end positioned in the vicinity of but normally separated from the second core element. In one embodiment of the invention, an armature of magnetic material is fastened to the spring so that the armature is positioned in the vicinity of the gap but normally separated from the two core elements. In another embodiment of the invention, the spring itself is formed from a magnetic material and serves as the armature. A stationary contact is positioned adjacent the spring and the spring is biased so that the spring normally engages the contact. And finally, an energizing coil is positionedaround the core elements, the spring, the armature, and the contact. The spring and first core element form a common terminal for the relay, the contact forms the normally closed switch terminal for the ay, and the second core element forms the normally open switch terminal for the relay. When the coil is de energized, a closed electrical circuit is provided between the fisrt core element and the contact. When the coil is energized, a closed electrical circuit is thenprovided' between the first core element and the second core element.

The invention will be better understood from the following description taken in'connection with the accompanying drawing and its scope will be pointed out in the claims. In the drawing:

FIGURE 1 shows a longitudinal cross-sectional view of a preferred embodiment of an electromagnetic relay in accordance with the invention, the view being taken along the lines 11 of FIGURE 2.

FIGURE 2 shows a transverse cross-sectional view of the electromagnetic relay taken along the lines 2-2 of F G R h.

FIGURE 3 shows an elevation view of the core elements and spring of the electromagnetic relay of FIGURE 1 dur'in g astage of manufacture of therelay;

FIGURE 4 shows a perspective view of an inner tube which supports the contact bar and core elements of the ay;

FIGURE 5 shows a longitudinal cross-sectional view of another'embodiment of an electromagnetic relay in accordance with the invention; and

FIGURE 6 show a longitudinal cross-sectional iew of another embodiment of an electromagnetic relay in accordance the invention.

In'the figures, the same reference numerals are used to refertothe' same'elem'ents; A longitudinal cross-sectional view of the complete electromagnetic 're'l'ay'is shown in FIGURE 1, and a transversecross-sectional 'view' is shown in FIGURE 2. The relay comprises a core having a first core element 12 and a second'core element 14'both'formed of a magnetic material such as soft iron. A material having low flux retention is preferable in order to aid dropout of the relay when the coil is de-energized. The first and second core'relements 12, 14 lar'eformed, in a manner which will be explained, from a blank 10' which is best shown in FIGURE 3. Integral with the core elements 12 14 are respective back' portions 16, 1-8 for supporting the relay structure and also for providing a good path for the magnetic fluX' of the relay coil. The core elements 12, 14' are separated by an air gap 19 which, as seen FIGURE 1, may be generally described as X-shap'ed', and which is formed by the free or inner end surfaces of the core elements 12, 14. An armature 20 is formed from the same blank 10 as the core elements 12, 14 and has a shape which corresponds to or substantially fits in a portion of the gap 19. The armature 20 is fastened to a spring 22 which in turn is fastened to the first coreel'e'ment 12 at the surface point 24 by any suitable means such as welding. The spring 22 is preferably made of a Hat elongated strip of resilient material such as beryllium copper, and is bent or shaped so that it rests substantially in the position shown in FIGURE 1. The spring 22 carries a spring contact 26 preferably formed of a high conductivity metal that is silver plated, the spring carried contact 26 being on the opposite side of the spring 22 from the armature 2i). The spring carried contact 26 normally (i.e., when the relay is released) engages a contact bar 30 which is also preferably formed of a high conductivity metal that is silver plated. The contact bar 30 has an extension which is bent to provide a backstop 32 for the free end 28 of the spring 22. The backstop 32 help to reduce bouncing or oscillation of the spring 22 when therelay is released or dropped out to its normal position. The free end 28 of the spring 22 is positioned in the vicinity of the second core element 14'but is normally separated therefrom. When the relay is energized and pulled up from its normal position, the free end 28 of the spring 22 engages a contact 34 which is preferably formed of iahigh conductivity metal that is silver plated, and which is'fastened to the second core element 14'. Since the free end 28 of the spring 22' provides an electrical circuit to the contact 34 on the second coreelement 14, and since the free end 28 may flex or whip when the relay is released or dropped out so that the free end 28 engages the backstop 32 before the spring carried contact'26 engages the contact bar 30, the entire spring 22 or at least the free end 23 portion may preferably be' plated or alloyed with a suitable high conductivity metal such as silver.

The contact bar 30 and its backstop 32 are supported by an inner tube 40, which is shown most clearly in the perspective View in FIGURE 4. The inner tube 451' is formed from a suitable piece of cylindrical, non-magnetic material such'as stainless steelso' that it has end supports 42, 44 which are joined by two strips 46. On the lower side and between the two strips 46, a semi cylindrical support 4.8 is provided. This support 48 carries the contact bar 30 and the backstop 32. The cOnt-act bar 3,0 is preferably fastened to the support 48 before the relay is assembled. The inner tube '40 is supported in an electrically'insulat'ed relation between the back portions 16, 18'0f the repective core elements 12, 14 by electrically insulating cylindrical beads 50 which surround the back'portions 16, 18 and bear against the shoulders formed by the first and second core elements 12, 14 respectively. The cylindrical 'beads 50 may be rigidly fastened to the back portions 16, 13, by any suitable means; Glass beads are preferred as they can be fused to the back portions 16, '18 to provide a hermetic seal. When in position, the inner tube 41) is outside the core elements 12 14, the back portions 16, 18, and the cylindrical beads 50. The inner tube 49 is supported by and rigidly fastened to the beads 50 by its respective end supports 42, 44. A cylindrical metallic tube 60 of nonmagnetic material surrounds the inner tube 40 and the relay elements. The cylindrical tube 60 may be fastened to the inner tube 40 around the entire circumference of the inner tube 41] at the end supports 42, 44 respectively under such conditions as to hermetically seal the moving relay parts under the most desirable conditions, such as in an atmosphere of dry inert gas. An operating or energizing coil 62 is wound around a suitable coil form 64, the coil form 64 being made of an electrically insulating material such as a plastic. The ends 66 of the coil 62 are brought out at one end of the coil form 64 for connecting the coil 62 to external terminals. The ends of the inner tube 40 and the cylindrical tube 60 are insulated by bushings 63 which are formed from an electrically insulating material such as a plastic and which are dimensioned so that they pass over the respective end portions 16, 18.

Suitable coil terminals 70 are provided and fastened to the ends 66 of the coil 62. Likewise, a switching terminal 72 is fastened tothe back portion 16, a terminal 74 for the normally open contact 34 is fastened to the back portion 18, and a terminal 76 for the normally closed contact bar 30 is fastened to the cylindrical tube 60. These various terminals 70, 72, 74, 76 may be supported by means of metallic discs 8i) which have openings for passing the terminals therethrough. The discs 80 are preferably made from a magnetic material to provide a better path for the magnetic flux between the coil 62 and the core elements 12, 14. The various terminals may be electrically insulated from the discs 80 by means of insulation bushings 81 formed from a thermally setting plastic which can be cast in the openings in the discs 80. The complete assembly is wrapped with an electrically insulating tape 82, then placed in a metallic outer cylinder 84, and separated therefrom and supported by a material 86 such as a thermally setting plastic which can be cast and which, when cool, becomes hard. The outer cylinder 84 is preferably made of a magnetic material to provide a better path for the magnetic flux between the coil 62 and the core elements 12, 14.

When the relay is in its normal or released position, the relay elements have the position shown in FIGURE 1. An electrically closed circuit is provided from the switching terminal 72 through the back portion 16, the first core element 12, the spring 22, the spring contact 26, the contact bar 30, the support 48, the inner tube 40, the cylindrical tube 61), and finally to the terminal 76 for the normally closed contact bar 30. An electrically open circuit exists between the switching terminal 72 and the terminal 74 for the normally open contact 34, since the second core element 14 and its back portion 18 are electrically insulated from the remainder of the relay elements. When the coil 62 is energized, however, such as by the application of a suitable potential to the coil terminals 70, the armature 20 is drawn up in the gap 19 towards the core elements 12, 14 until the free end 28 of the spring 22 engages the contact 34. The armature 20 continues to be drawn up into the gap 19 until the faces of the armature 20 contact the corresponding end surfaces of the core elements 12, 14. This over-travel of the armature 20 provides a desirable wiping of the free end 28 of the spring 22 across the contact 34. An electrically closed circuit is thus provided between the switching terminal 72 and the terminal 74 through the back portion 16, the first core element 12, the spring 22, the free end 28, the contact 34, the second core element 14, the back portion 18, and the terminal 74. An electrically open circuit then exists between the switching terminal 72 and the terminal 76 in this condition because the spring contact 26 is disengaged from the contact bar 34 With the'armature 2t) contacting the core elements 12, 14, a good magnetic path is provided between the core elements 12, 14-, and the energizing coil 62. This path includes the outer cylinder 84, the righthand disc 80, the back portion 16, the first core element 12, the armature 241, the second core element 14, the back portion 18, the left-hand disc 86, and the outer cylinder 84. However, a gap of non-magnetic material remains between the outer cylinder 84- and the discs so that the relay will drop out readily when the coil 62 is de-energized.

The relay described has been successfully built and operated in an embodiment having very small physical dimensions. This embodiment had an over-all length of approximately 0.89 inch and a diameter of approximately 0.26 inch. Electrically, this relay was capable" of switching a current of approximately 1 ampere at 28 volts through at least severel hundred thousands of cycles of switching. It will be appreciated that the invention provides a relay which has small physical dimen sions but which is durable and rugged. Furthermore, maximum utilization of the magnetic field is attained by the general arrangement and by the armature being near the center of the coil. 1

The assembly of a relay having the small physical dimensions just described might, under mass-production conditions, normally be expected to be dimcult. However, a relay in accordance with the invention is relatively easy to construct and assemble. The ease of construction and assembly results, at least partially, from the novel core blank 10 shown in FIGURE 3. This case also resuits from the method by which the core elements 12, 14 and the armature 21 are formed, and by which the spring 22 is aligned with and fastened to the first core element 12. A cylindrical core blank 10 having the configuration shown is ground or machined along parallel planes to provide the fiat surfaces 24, 25. If the flat surfaces are formed in one operation, accurate alignment of all the elements to be fastened to the blank 10 is thus assured. After the fiat surfaces 24, 25 are formed, two slots or kerfs 21 are formed in the flat surface 25 on each side of the material in the blank 10 that will form the armature 20. The angle between the slots 21 may vary over a wide range, namely from zero (in which case the slots are parallel to each other) to an angle approaching 180 degrees. However, it is preferred that the slots 21 conyerge at an angle of degrees, which represents a good compromise for the various design factors involved. T contact 34 is then fastened to the fiat surface of the second core element 14. The spring 22, which has already been provided with its contact 26 and a welding button 27 (if needed), is fastened to the flat surface between the grooves 21. Then, the spring 22 is provided with a suitable mechanically biasing bend near the end which-will be attached to the flat surface 24 of the first, core element 12. And then, the end of the spring 22 is suitably fastened to the first core element 12 at the surface 24. After these operations are complete, the beads 50 are fastened to the back portions 16, 18. The inner tube 40, to which the contact bar 30 has been previously fastened, is then passed over the blank 10 and positioned so that the contact bar 30 is adjacent and parallel to the contact 26. This positioning is easily attained. The inner tube 40 is then fastened to the beads 50 by suitable means. Then, the blank 10 and the inner tube 40 are supported in a. suitable jig or fixture, and the blank 10 is ground ormachined along the dotted lines shown in FIGURE 3 so: that the material 11 enclosed by the dotted lines is re-- moved. When this material 11 is removed, the armature 20 is freed from the blank 11), this operation also forming. the first and second core elements 12, 14, and the X- shaped air gap 19 bounded by the inner end surfaces of:

the 'core elements 12,14. The various elements are held in'the proper alignmentby theinner tube 40after the material Ills-removed. -'Ihe-'relay is completedby adding the other elements including the cylindrical tube 60, the:coil' 62,'the end portions, the terminals, and the outer cylinder'84. In addition to holding the various elements in alignment, the inner tube til per'rnits access to the elements-through theopenings betwee'n'the strips 4 6 so that the 'm'ater ial ll 'can be easily removed and so that'the certain elements, such as spring 22 can be adjusted if necessary. The ease of assembly and alignment of the relay elements in accordance with-the-meth'od described makes the manufacture of such "rel'ays-feadily adaptable to' mass mducti 'nt chniques.

Thesteps iil'tlle methe'd described my be varied, if de- -sired,';a s follows': After' the slot or -kerfs 21 are formed, acementsuch-a's an epoxy cement is putinthe slots 21, and the material 11 is then removed. After this, the spring 22 and thebeadseil are added. A Then the inner tube 40 is pas's'etl over theblankIO andthe'b'eads '50 and positioned so that the contact bar St} is adjacent and parallel to the'contact 2 6. Then, a solvent is applied to dissolve the cement in'the slots 21, thus freeingthe armature 2t). For the cement mentioned, a suitable solvent would be dichloroinethane.

FIGURE: 5 shows ;a jlo ngitndina l cross-sectional view of another 'embodiment'of an electromagnetic relay inaccordance withthe invention, the embodiment of FIGURE 5 being similar to the em'bodimentpreviously described. In FIGURES, elements substantially identical to those in FIGURE '1 have the same reference numerals, and corresponding elements which may be somewhat different in form have the same reference numerals with a rime suffiked" thereto. FIGURE 5 does not show the complete electromagnetic relay, but shows only 7 that portion which wonld be assembled within'the 'coi'l'form 64 and coil 62-: The" embodiment 'ofFIGURE S includes first and second core elements 1 2', 1ft having respective ba'ck portions"1"6"f, 1s. Beads 50 surround the back portions 16', 1 8 and support the inner tube 40; The nonmagneticcylindrical tube '60 surrounds the inner tube 40' andthe relay elements. A flat spring ZZ isfas'tened to the first core element 12 atthe' surface point 2 1 by any suitablemeansfsuchas welding. In the embodiment of FIGURE 5, the spring 22' serves as the armature of the relay, and hence is, m'ade'of a magnetic material which" is also" resilient1 I An example of such material isspring steel. The's'pring 22 carries two contacts 26, 29 which'are fastened to opposite'faces' of the spring 22' at a point between the first and second core elements 12', 14. The'sp r'ing 22' is bent or mecha'nically biased so that its contact 26 normally engages the contact bar 30' which is fastened to the semi-cylindrical support 43. A contact 34' is supported in mean gap 119 by a contact support 35 which is fastened to the second core element 14. The spring 22, its contacts 26, 2?, the contact bar 30, and the contact 34' are all positioned and arranged so that thespring contact 26 normally engages the contact bar 30' when the relay is de-energized, and so that the spring contact 29 engages the contact 34' when the relay is energized or pulled up from its normal position. And, it is preferable that the parts be arranged so that there is a wiping action between the contacts, and so that the spring 22 makes contact with the second core element 14'. Since the spring 22' comprises a magnetic material, a good flux path is provided between the first and second .core elements 12, 14 when the relay is energized.

The method of assembling the embodiment shown in FIGURE 5 is similar to the method described in connection with the embodiment shown in FIGURE 1. A blank of magnetic material having the configuration shown in FIGURE 5 is ground or machined along parallel planes to provide the flat surfaces needed for attaching the spring 22 and the contact support 35. The beads 50 are fastened to the back portions 16, 18'. The inner tube 40, to

which the contact bar 30' has been previously fastened, is then passed over the blank, and fastened to the beads 50 in such aposition that the contact bar '30 is adjacent andp'arallelto the surface 24' to which the spring 22 willbe fastened. Material is then removed from between the portions of the bla'nk which will formthe core elements 12', 14 so as to form the air gap 19', The openings between the strips 4'6 of the inner tube 40 readily permit this operation. After the air gap 19 is formed, the spring 22 with its cbntacts 26, 29 isfaste'nedto the first core element 1 2 at the surface point 2'4. And finally, the contact support 35 with its contact 34" is fastened to the second core element 14'. Then the relay may be completed as described in connection with FIG- UREl. V l a a FIGURE 6 shows the embodiment of FIGURE 1 used in connection with a polarized relay. In FIGURE 6, elements whichcorrespond'to those in FIGURE 1, but which may be somewhat different in form, have the same reference numerals with-a'double prime suffiiied thereto The relay shown in FIGURE 6 is essentially comprised of two of the working relay units shown in FIGURE 1, namely, two first core elements 12", two second core elements 14", and two'arrnatures 20'. These elements are positioned along parallel lines withthe same elements corresponding'ly located. They are held in position by electr'ically ins'ulatirig'members' positioned at their respective ends, the members 99 having openings to receive and firmlyhold the core elements I2", 1 1'. A spring 22" is fastened at one end at corresponding points 'on first core elements I2. The free end of the spring 22" is positioned in the vicinity of the contacts 34" which in turn are fastened at corresponding points on the second core elements 147. The spring 22 is alsofastened to the two armatures 20" at a point intermediate its two ends. In operation, the spring 2 moves np ordown to engage either 'of fthe twocontactsfi t and provide an electrical connection "from the switching terminal to either terminal No. 1 or terminal No. 2.

If the relay shown FIGURE '6 is to operateas a polarized relay, fonr permanent magnets 591-94 are provided at each'of the respective ends of the core elements 12", 14". These permanent magnets Ell- 4 are formed of seini-circnlar flat] plates, each of which has a semicircular opening therein that is'ada'pted to be attached to the ends of the, core elements 12", 14". The four permanent magnets 91-94 are arranged with their polarities as shown, and so that the two magnets at each end form a substantially circular frame to support a housing for the relay. If "the relay coil 62" is de-energized,,the magnetic fiuxbetween the lower set of magnets 91, 92 is substantia'lly equal to the magnetic flux between the upper set o'fma'g'n'et's 93, 941 However, the spring22 will move toward and engage one of the contacts 34", and remain inthis position, In FIGURE 6,1it is assumed that the spr 22" moveddownwardl If the relay coil '62" is energized with one direction of current, so that the magnetic flux provided by the coil 62" opposes the magnetic flux between the lower set'of magnets 91, 92 by substantially the same amount of flux, and aids the magnetic flux between the upper set of magnets 93, 94, then there is very little, if any, magnetic flux in the lower armature 20 and a relatively large magnetic flux in the upper armature 20". Consequently, the spring 22" moves upward. This pro vides an electrical connection from the switching terminal to terminal No. 1. However, if the direction of current flow through the relay coil 62" is reversed with respect to the original current direction, then the spring 22" will move downward to provide an electrical connection between the switching terminal and terminal No. 2. Thus, polarized operation of a relay in accordance with the invention is provided.

The method by which the relay shown in FIGURE 6 can be manufactured is substantially similar to the method explained in connection with the assembly of the relays shown in FIGURES 1 through 5. The core elements 12", 14", the armatures 2d", and the spring 22." are assembled and held in position by the inner tube 40'. The inner tube 40 does not have the semi-cylindrical support 43 shown and described in connection with the relays of FIGURES 1 through 5, as the contacts 34 for the spring 22" are carried by the second core elements 14". With the relay units housed and fastened within the inner tube 40", the armatures are freed by machining or grinding, thus providing and insuring the alignment desired. One slight difference might be mentioned in connection with the embodiment of FIGURE 6, namely the shape of the air gaps. In the embodiment shown in FIGURE 6, after the slots have been cut into the respective blanks, and the blanks fastened in the inner tube 40", the armatures 24)" are freed by removing material in such a manner that the slots are, in effect, continued through the blanks to providethe air gap shape shown. However, this feature is one of design and choice, and may be varied to a great extent without departing from the spirit of the invention.

From the above description, it will be seen that a relay in accordance with the invention may have relatively small physical dimensions and may be manufactured with massproduction methods.

While the invention has been described with reference to particular embodiments, it is to be understood that modifications may be made by persons skilled in the art without departing from the spirit of the invention or from the scope of the claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A method of manufacturing a portion of an electromagnetic relay from a blank to provide a pair of core elements separated by a gap, said relay having a springsupported armature positioned in the vicinity of said gap, comprising forming a plurality of substantially fiat and parallel surfaces on one side of said blank, forming a pair of slots in said blank at one of said flat surfaces, said slots extending partially into said blank, fastening said spring at a point intermediate the ends thereof to said one fiat surface at a point between said slots, fastening one of said ends of said spring to another of said flat surfaces, and removing a portion of said blank in the vicinity of said slots to free the material between said slots from said blank and form said core elements.

2. A method of manufacturing a portion of an electromagnetic relay from a blank to provide a pair of core elements separated by a gap, said relay having a springlike armature, comprising forming a substantially flat surface on one side of said blank, fastening said spring-like armature at one end thereof to said fiat surface, supporting the ends of said blank in a fixed relationship, and removing a portion of said blank in an area intermediate the ends thereof to form said core elements.

3. A method of manufacturing a portion of an electro magnetic relay from an elongated blank to provide first and second core elements which are separated by a gap, said relay having an armature that is positioned in the vicinity of said gap and that is supported by a flat spring, comprising forming at least two substantially plane surfaces on one side of said blank that are substantially parallel to each other and to the longitudinal axis of said blank, forming, in said blank at one of said surfaces, a pair of slots which extend partially into said blank, fastening one flat face of said spring at a point intermediate the ends thereof to said one surface at a point between said slots, fastening said flat face of said spring at one end thereof to said other surface at a point removed from said slots, supporting the ends of said blank in a fixed relationship, and removing a portion of the material of said blank in the vicinity of said slots to free the material between said slots from said blank, thereby forming said armature and said core elements.

4. A method of manufacturing a portion of an electromagnetic relay from an elongated blank to provide first and second core elements which are separated by a gap, said relay having an armature that is positoned in the vicinity of said gap and that is supported by a flat spring, comprising forming at least two substantially plane surfaces on one side of said blank that are substantially parallel to each other and to the longitudinal axis of said blank, forming, in said blank at one of said surfaces, a pair of slots which extend partially into said blank from said one surface but which do not meet, filling said slots with a dissolvable cement, fastening one flat face of said spring at a point intermediate the ends thereof to said one surface at a point between said slots, fastening said one face of said spring at one end thereof to said other surface at a point removed from said slots, removing a portion of the material of said blank in the vicinity of said slots to eliminate the material between said slots from said blank, supporting the ends of said blank in a fixed relationship, and dissolving said cement from said slots, thereby forming said armature and said core elements.

5. A method of manufacturing a portion of an electromagnetic relay from an elongated blank to provide first I and second core elements which are separated by a gap,

' said relay having an armature that is positioned in the vicinity of said gap and that is supported by a flat spring, comprising forming at least one substantially plane surface on one side of said blank, forming, in said blank at said one surface, a pair of slots which extend only partially into said blank, fastening one flat face of said spring at a point intermediate the ends thereof to said one surface at a point between said slots, fastening said flat face of said spring at one end thereof to said blank at a point removed from said slots, supporting the ends of said blank in a fixed relationship, and removing a portion of said blank in the vicinity of said slots to free the material between said slots from said blank, thereby forming said armature and core elements.

References Cited by the Examiner UNITED STATES PATENTS 2,481,003 9/49 Curtis 20087 WHITMORE A. WILTZ, Primary Examiner.

JOHN F. CAMPBELL, Examiner. 

2. A METHOD OF MANUFACTURING A PORTION OF AN ELECTROMAGNETIC RELAY FROM A BLANK TO PROVIDE A PAIR OF CORE ELEMENTS SEPARATED BY A GAP, SAID RELAY HAVING A SPRINGLIKE ARMATURE, COMPRISING FORMING A SUBSTANTIALLY FLAT SURFACE ON ONE SIDE OF SAID BLANK, FASTENING SAID SPRING-LIKE ARMATURE AT ONE END THEREOF TO SAID FLAT SURFACE, SUPPORTING THE ENDS OF SAID BLANK IN A FIXED RELATIONSHIP, AND REMOVING A PORTION OF SAID BLANK IN AN AREA INTERMEDIATE THE ENDS THEREOF TO FORM SAID CORE ELEMENTS. 